654 Caldwell's automatic microtome. 



bottle a saturated tissue can be temporarily covered by the 

 chloroforirij while tissues containing alcohol keep steadily on 

 the surface. 



When the tissue is saturated with the etherised chloroform 

 it should be transferred to pure chloroform and there left for a 

 few minutes. Then drop in some pellets of soft paraffin and 

 leave it for two hours or more, shaking occasionally. The 

 whole should then be poured into a small melting pot and a 

 quantity of embedding material added. The melting pot should 

 then be placed in the water bath at a temperature of about 

 60° C, and there left until all the chloroform has evaporated, 

 which may be determined by the absence of smell of chloroform 

 on shaking. If much embedding material is required this 

 process takes a day or two; it is therefore better, when the 

 solution of embedding material is fairly strong, to take out the 

 tissue and put it direct into pure melted embedding material. 

 In any case no chloroform must remain in the material to be 

 cut, as it makes it brittle. Generally speaking the more 

 gradually these processes are passed through the better will be 

 the result. 



